The Offshore Voyaging Reference Site

Keeping The Water Flowing

Left to my own devices I could happily be a lazy guy, but that’s by no means a good thing to be when you’re in charge of a boat. When running charter boats that are in daily use, daily, weekly and monthly maintenance check lists are absolutely de rigeur to ensure that, random mechanical failure apart, the boat (and most particularly the engine) functions effectively.

There’s no consequential loss insurance available in this regard—blow the engine up through simple carelessness and that’s you out of the game. And it’s even more important when you’re in out of the way places.

So every day I check the oil level, water level, raw water filter strainer and belt tension, and have a good look around under the engine for any signs of leaks or stray nuts and bolts. This simple detective work has saved me endless hours of grief, through nipping many an impending catastrophe in the bud. And every time we start the engine, we check that the exhaust is pumping cooling water—just in case.


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John Harries

Hi Colin,

A post full of really useful information, as always. I really like the wire tie to compress the blades for installation tip. I must have replaced thirty or so impellers over the years, but I have never thought of that.

Colin Speedie

Hi John

I can’t remember where I picked it up – probably somebody trying to stop me turning the air blue as I fiddled with installing an impeller the old fashioned way!

Best wishes

Colin

Marc

Funny, I installed a replacement one of those plastic “basket” strainers on my 33 footer just yesterday. I think you’ve finally convinced me to order a couple of Speedseal kits, one for my old Atomic 4 and the other for my new Beta 60 on the steel boat. And an impeller puller; I use a prop puller, and this is basically the same thing, so I don’t know why I’ve put it off.

The cable tie idea is brilliant. I owe you a pint for that.

I wonder if, while we are on the topic, you have an opinion on the idea of standpipes that rise above the WL. The boat builder for my steel boat welded one amidship, just offset to one side. There are four one-inch, seacocked T-offs for engine cooling water (it goes to a Perko and then to the raw water pump), one for the head and one to a March pump for use by the A/C unit, plus a spare. The real advantage is that you can physically clear out the pipe from above, and from inside the boat. A previous owner sucked in a fish, noticed the engine temperature was rising, and solved the issue with a broomstick! I am considering a hinged strainer plate to perhaps deter critter and bag ingress, properly insulated from the steel hull, of course.

I rarely see standpipes on private boats, and I’ve often wondered why. A heavily glassed in version would be as strong as the Schedule 80 pipe from which mine is made.

Colin Speedie

Hi Marc

I think the standpipe/manifold idea is absolutely the best way to handle seacocks there is. And the only builder I’ve seen who does it that way is Boreal.

With a manifold on stand pipes you can have easy access to the seacocks, and they’re up where they should to remove them if necessary without sinking the boat! What’s not to like? Every builder offering ocean going craft should be considering just this.

In fairness, I once saw a Rival (many years ago) with a similar installation, but I can’t tell you if it was standard or an owners choice.

Glad you liked the post – I’ll look forward to the pint!

Best wishes

Colin

John Harries

Hi Marc and Colin,

Stand pipes sound like a great idea. However there is one big drawback to be aware of: You don’t want them if you have any intention of keeping the boat in the water in a place where it freezes. The reason being that the water will freeze in the standpipe and blow hole in it, thereby sinking the boat. I have a friend who lost a boat in Norway in just this way.

As an aside: if you do want to freeze in at all, the through hull fittings need to be custom turned with a slight taper as they go up to the seacock, what an engineer would call “drift”. The result is that a plug of ice is pushed out as it expands. Many Dutch metal boats are so fitted.

Colin Speedie

Hi John

Thanks for that very sensible heads-up!

Best wishes

Colin

Marc Dacey

Once again, a nugget (bergy bit?) of information that I have NEVER heard elsewhere…and yet seem perfectly obvious to any Canadian…or anyone who has overfilled an ice cube tray.

The taper idea is great. I have no idea if our standpipe features it. It’s exchanges like this that make this website invaluable, even if overwintering in Norway is not on our bucket list. Heck, it might be one day.

Victor Raymond

I have four standpipes on my Meta Dalu 47 and I believe this is standard practice for this yard. I will have to check to see if they are tapered or not. Brilliant idea!
I suppose one could also fill the void with a crushable sacrificial tube that would take up volume when inserted but absorb the ice expansion. Even a length of tubing sealed at both ends would work. Will need lots of signage though as a the brain thaws out.:)

John Harries

Hi Victor

Just to clarify, I did not suggest drift in a stand pipe. What I said was that a normal sized though hull with drift will not have problems with freezing.

I doubt that you could put enough drift in a stand pipe that was long enough to extend above the waterline. Also, if there was even a slight bend in the pipe, there could be issues.

So my recommendation for boats that will freeze in is no stand pipes, at least until I hear from a credible source who has had stand pipes and has frozen in.

Victor Raymond

Ok here is the solution. Once you have decided to freeze in then correctly sized closed cell “backer rod” http://www.h-b.com/index.php?main_page=product_info&products_id=213 is inserted into the standpipe. Whatever little water not displaced by the backer rod will freeze and squeeze the backer rod. It is very simple and inexpensive and weighs almost nothing. A 100 foot roll is about $15.

John Harries

Hi Victor,

Sounds like a great solution, although I would want to test it with a piece of pipe in a freezer before trusting my boat to it. And don’t forget to take them out in the spring, particularly before flushing the head!

Scott Flanders

Very well written and illustrated. I have one additional comment. Years ago we had a sea nettle problem in the Chesapeake and were cleaning the sea strainers every other day. The cure was removing the traditional scoop strainers and replacing them with Sen Dure scoop strainers that have 1/8″ holes on 1/8″ centers. In the years since we have had zero issues with debris in the strainers. The strainer for a 3/4″ pipe thru hull is #905 and measures 6 1/4″ x 3″. Centrifugal pumps face the strainer wedge forward and rubber impeller pumps face the strainer heel forward.

Colin Speedie

Hi Scott

I haven’t come across these strainers before, so i’ll be sure to look them up. In fact, we don’t have an external strainer at all, as I’ve seen more problems with them than without! It’s also true that most are bronze and so out of the question for an aluminium hull – plastic versions, maybe, if attached with care.

Best wishes

Colin

Chris

Our builder delivers (well did, the economy drove him out of business) a fiberglass 47 footer with a sea trunk (closed standpipe) standard. When when we discussed freezing, it sent me off to research.

When seawater freezes it seeks to expand in volume by about 9%. If one has a 15cm dia standpipe and if one ignores pressure relief from upward and downward expansion, the ice would seek a diameter of 15.66cm. If we include a 25% safety factor (expansion of 11.25%) the diameter sought would be 15.82cm. This would equate to .41 cm on opposite sides of the standpipe. The transmission cable people have adopted compressible liners to deal with compression from external freezing. Seems to me the converse could be done in this situation — line the standpipe as needed with something that can be compressed more than .5cm. One could even conceive of running a capped off section 0f large hose through the length of the standpipe to reduce the ice expansion to tolerable within the structural limits of the material used and still allowing flow. These ideas are passive.
One could also actively circulate the water in the standpipe and the probability of freezing drops to near zero. It takes very little motion to keep seawater from freezing because of the freeze dynamics involved.

The other solution I once heard of was the owner made a thick, temporary piston and pushed it to the bottom of the standpipe and then added non-toxic antifreeze above the piston. But that’s heresy from a gathering of cruisers — a dodgy group at times.

Ben Eriksen

Yes, thanks — 3 great tips here which I’ve written down on the pre-delivery checklist.

Colin Speedie

Hi Ben

My pleasure!

Colin

Colin Farrar

Thanks for the wire tie idea!
Recently I’ve been able to buy impellers (Jabsco, I believe) that have a female pipe thread in the hub. This allows me to spin on a homemade T handle for pulling the impeller.

Colin Speedie

Hi Colin

That’s a new one on me, but it sounds like a good idea, as does your own solution – anything to avoid getting the screwdrivers out!

Best wishes

Colin

Roland

Great post.
Thanks for the tip how to compress the blades.
When you are replacing the impeller also check the inside of the cover plate for wear. It is not unusual that you see wear. If to deep the pump will not work. You can sand the surface down. As an emergency fix you can use the other side of the cover plate. But important to remember. If the cover plate has signs of wear, it is also likely the other side of the impeller is worn.

Colin Speedie

Hi Roland

Good point, and periodic inspection of the back plate is also a good idea, too.

I’ve kept the original face plate of the pump (which is virtually unused) and a spare gasket or two for just such an eventuality.

See also the comments below on the new product from Speed Seal, which sounds like a good idea.

Best wishes

Colin